The present invention relates generally to computed tomography imaging and, more particularly, to a detector cell for sensing thermal changes in response to the absorption of HF electromagnetic energy for use with computed tomography systems.
Typically, in computed tomography (CT) imaging systems, an x-ray source emits a fan-shaped beam towards a subject or object, such as a patient or a piece of luggage. Hereinafter the terms “subject” and “object” shall include anything capable of being imaged. The beam, after being attenuated by the subject, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is typically dependent upon the attenuation of the x-ray beam by the subject. Each detector element of the detector array produces a separate electrical signal indicative of the attenuated beam received by each detector element. The electrical signals are transmitted to a data processing system for analysis which ultimately results in the formation of an image.
Generally, the x-ray source and the detector array are rotated about the gantry within an imaging plane and around the subject. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal point. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector, a scintillator for converting x-rays to light energy adjacent the collimator, and photodiodes for receiving the light energy from the adjacent scintillator. Each scintillator of a scintillator array converts x-rays to light energy. Each scintillator discharges light energy to a photodiode adjacent thereto. Each photodiode detects the light energy and generates a corresponding electrical signal. The outputs of the photodiodes are then transmitted to a data processing system.
With these known scintillators, the scintillating component must be of sufficient thickness to generate the requisite efficient x-ray detection. As a result, a minimum scintillating material thickness is necessary for proper signal to noise generation by the photodiode. The minimum requirements yield higher costs as well as limit the ability to reduce the overall detector cell size and spatial resolution of the detector. Furthermore, detection inefficiencies in this two step detection process, x-rays to light and light to electrical signals, has efficiency losses resulting in a diagnostic image of poorer quality or lower sensitivity.
High density materials may be advantageously used in a detection cell as these materials may absorb HF electromagnetic energy in relatively thin cross-sections. As a result, smaller detector cells can be fabricated increasing system resolution. Moreover, use of materials that change in temperature upon the absorption of HF electromagnetic energy allows for use of thermal sensing components rather than photodiodes thereby producing output signals more indicative of the HF electromagnetic energy detected resulting in a more sensitive and a diagnostic image of greater sensitivity.
It would therefore be desirable to design a detector cell for sensing thermal differentials in the detector cell resulting from the absorption of HF electromagnetic energy thereby providing improved, higher resolution, and more sensitive detector signal output to a data processing system of a CT system.